Torque converter

Abstract

A torque converter includes a front cover, an impeller, a turbine and a stator. The impeller includes an impeller shell coupled to the front cover, a plurality of impeller blades disposed inside the impeller shell, and an impeller hub. The impeller hub is formed in an axially extending tubular shape, while being fixed at an engine-side end part thereof to the inner peripheral part of the impeller shell by means of friction welding. The impeller hub also has a burr produced by the friction welding.

1 . A torque converter, comprising:
 a front cover coupled to an engine-side member;   an impeller into which a torque from the front cover is inputted;   a turbine disposed in opposition to the impeller; and   a stator disposed between an inner peripheral part of the impeller and an inner peripheral part of the turbine, the stator being configured to control a flow of an operating fluid flowing from the turbine to the impeller, wherein   the impeller includes   an impeller shell coupled to the front cover;   a plurality of impeller blades disposed inside the impeller shell; and   an impeller hub formed in an axially extending tubular shape, the impeller hub being fixed at an engine-side end part thereof to an inner peripheral part of the impeller shell by friction welding, the impeller hub having a burr produced by the friction welding.   
     
     
         2 . The torque converter recited in  claim 1 , wherein
 the impeller shell has an inner peripheral extending portion formed on an inner peripheral end thereof extend and extending to a further inner peripheral side than an inner peripheral surface of the impeller hub, and the inner peripheral extending portion restricting the burr produced by frictionally welding the impeller hub to the impeller shell from being produced on an engine side across the impeller shell.   
     
     
         3 . The torque converter recited in  claim 1 , wherein
 the front cover has a friction surface on an impeller-side lateral surface thereof,   the torque converter further includes a lock-up device, the lock-up device being disposed between the front cover and the turbine, the lock-up device directly transmitting the torque from the front cover to the turbine,   the lock-up device includes   a piston having a friction member configured to be pressed onto the friction surface of the front cover, the piston being configured to be axially movable;   an output-side member fixed to the turbine; and   an elastic member elastically coupling the piston and the output-side member in a rotational direction, and   a part of the piston being processed with surface hardening, the processed part being configured to be slid with another member.   
     
     
         4 . The torque converter recited in  claim 3 , wherein
 the friction surface of the front cover is not processed with polishing.   
     
     
         5 . The torque converter recited in  claim 1 , wherein
 the plurality of impeller blades have a plurality of protrusions on impeller-shell side outer peripheral parts thereof, and the impeller shell has recessed portions into which the plurality of protrusions are inserted on an inner peripheral surface thereof, and   the plurality of impeller blades are fixed to the impeller shell by swaging lateral parts of the recessed portions.